Everything You Need To Know About Lactic Acid

Lactic acid: is it responsible for muscle pain and how to reduce its production?

Iva JovicSeptember 10, 201510:39 am

Our body tends to generate energy (ATP), whenever possible. While resting, 70% of ATP body gets from fat, 30% from carbohydrates and in aerobic way. However, when physical activities grow, our body chooses the source from which it will generate energy.

When physical activity is harder, needs for ATP are overcome and our body does not have enough oxygen.

If that is the case, then our muscles create energy in anaerobic pathway, which means the main substrate is not air but glucose.

ATP

Energy (ATP) is obtained from glucose, through the glycolysis process. It is the metabolic pathway that converts glucose into pyruvate. The free energy released in this process is used to form the high-energy compounds ATP and NADH. This process is taking place in the mitochondria of the cell.

On the contrary, when there is not enough oxygen, pyruvate enters into anaerobic degradation pathway and the result is lactate (the salt of lactic acid).

A muscle can prolong creating energy between 1 and 3 minutes, through anaerobic pathway, and for that period of time, the concentration of lactate increases.

Side-effect of lactate is acidification of the muscle cells (acidosis) and this acidic environment disables glycolysis process. It seems illogical that muscle is creating something that will reduce its ability to work properly but in fact, it is a natural defense mechanism.

It prevents permanent damage which would occur due to great stress, so it is a necessary process of slowing down of the process of muscle contraction. When the body rests and recovers, oxygen becomes available again and the lactate transits to pyruvate. This enables continuation of aerobic metabolism which is necessary for recovering the body from physical stress activities.

Lactates are ’raw material’ for ATP, especially for fiber type muscles and also heart muscle. Liver can also turn ATP into glucose, which is known as Cori cycle.

Muscle pain

Contrary to popular belief, lactates are not responsible for pain that might occur after working out. The truth is somewhat different…Lactates and some other products which occur are responsible for uneasy feeling we might have during the workout, but they are not responsible for the DOMS (delayed-onset muscle soreness) which occur 24-72 hours later.

In other words, the concentration of lactates in the blood is measurable and researchers have concluded that in the period after the workout, the levels of lactates are insufficient to cause DOMS.

Speaking of measurability, let’s mention some figures. When the body is resting, the concentration of lactates in blood is low, between 0,5 and 2,2 mmol/L.

Production of lactates increases with increased intensity of workout and also depends on fiber muscle type. Greater production is in correlation with type 2 muscle fiber, which is also connected to greater concentration of glycolytic enzymes in this type than in type 1.

Highest concentration of lactates in blood is about 5 minutes after a workout. Concentration of lactates is back to normal level within an hour. Light activity after training helps faster drainage of lactate. Therefore, changes in the concentration of lactate in the blood can be represented graphically in the form of curves. On such a curve, two moments stand out:

Lactate Threshold – LT: marks the maximum intensity of activities at which the speed of creation of pyruvate does not exceed the rate of oxidative phosphorylation (making ATP via aerobic pathway). When it exceeds the threshold, the concentration of lactate in the blood was significantly increased compared to the values in the standby mode. Moment of transition from aerobic to anaerobic mode occurs typically at 50-60% VO2 max for people who are not “in training”, and at 70-80% VO2 max in trained athletes. Threshold of expressed concentrations of lactate (onset of blood lactate accumulation – CLOUDY) – usually occurs when the concentration of lactate about 4 mmol /L

Hydration

If you want to lower the lactate production, here are some advices to follow:

Always drink plenty of water. Lactates melt easily so if you drink enough water, there is less possibility the pain will occur

Increase the workout frequency. Muscles can develop tolerance to lactates

If your workout is running, riding a bike or similar, slow down the tempo is you start feeling pain.

Finally, an experience that will be of great benefit to all athletes, especially those related to the gym is a direct link between the production of lactic acid and release of growth hormone (GH). More lactate is created (and with more GH) if you put emphasis on the eccentric (negative) phase when lifting weights.